Structural unit



- June 19.45- A. w. FRANKLIN I ,40

wmmTUM-Lv UNIT Fiied March 24 1945 vENTo ALB T W. FRANKLIN ED LF W Patented June 4, 1946 UNITED STATES PATENT OFFICE STRUCTURAL UNIT Albert W. Franklin, New York, N. Y. Application March 24, 1945, Serial No. 584,523

3 Claims. (Cl. 250-14) This invention relates to a novel structure unit comprising a sheet of material having superposed thereon a sheet of metal or the like which has been simultaneously formed into a predetermined conilguration and attachd to the underlying supporting sheet.

This invention more specifically relates to antenna construction as employed in connection with radio apparatus and particularly with radio receivers.

An object of this invention is to provide a novel form of antenna structure for this purpose.

More specific objects of the invention are con- .cerned with antenna structure and a method of producing it whereby it may be manufactured at extremely low cost on a mass production basis by the use of simple automatic machinery.

It is, therefore, another object of the invention to provide a structurally simple antenna which is exceedingly inexpensive to manufacture.

A still more specific object of the invention is to provide a combined antenna and back or housing closure for radio receiving sets comprising a single unit.

Other objects of the invention will be apparent from the following disclosure of the single embodiment thereof illustrated in the attached drawing.

This invention resides substantially in the combination, construction, arrangement and relative location of parts, as will be described in detail below.

In the accompanying drawing- Figure 1 is a plan view of a combined radio receiving set back or closure and antenna unit:

Figure 2 is an edge elevational view of the unit; and

Figure 3 is a cross-sectional view taken on the line 3-3 of Figure 2 and including a diagrammatic illustration of a portion of the stamping die by means of which the antenna is formed.

In modern radio receiving sets, particularly of the type used for broadcast reception, the electrical components are contained within a decorative housing or cabinet. Such cabinets are usually constructed with a removable back or closure to facilitate access to the interior for repair and replacement of parts.

It is also common in the present day manufacture of such sets to include a built in antenna usually in the form of a loop antenna of such particular configuration as to make it physically compatible with the space provided therefor. These antennas as now'made are usually in the form of wound, single layer. open coils supported by some form of spider structure to hold the turns in spaced relation. Without going into detail, it will be apparent, particularly from the following disclosure of this invention, that the manufacture of such wound coils is relatively expensive particularly because of the labor item which is the largest item of cost in the manufacture of these and similar devices.

In accordance with this invention the labor factor is reduced, it is believed, to an absolute minimum with the result that the cost of manufacture of the unit has been greatly reduced.

As illustrated in the drawing, a panel I0 is of some suitable insulating material oi which there is a wide range and variety of products commercially available on the market. For example, it may be made of pressed fiber board, plastic and thermosetting materials, wood and the like. specific examples of suitable commercial products so are "Bakelite," Masonite, Vulcanite and the like. The panel It will, of course, be made of suitable configuration to fit on or in the back of the cabinet of the radio receiving set of which it is to become a part and, as illustrated, will usually as consist of a simple rectangular sheet of the material of the proper thickness. Secured in any suitable manner on what will be the inner face of the panel I 0 is a thin sheet II of some suitable conducting material such as copper, aluminum, and the like. The sheet I! will serve its intended purpose if it has a thickness or the order of a few thousandths of an inch and it may be attached to the panel I in any suitable manner as, for example, by means of rivets or bolts I! or, if desired, the parts ill and I! can be attached together by means of an adhesive. In the practice of this invention, it is probable that the parts l0 and I2 permanently bonded together will be available as a commercial product.

In accordance with the embodiment illustrated in the drawing, the sheet I! of metal is processed in one operation to form it into a continuous band in the form of convolutions of gradually decreasing diameter and of any suitable and practical configuration. As illustrated in the drawing, the metal sheet 12 has been cut into concentric convolutions I! of generally rectangular form. In the process of cutting the sheet, the convolutions are spaced from each other by an air gap H. The inner terminal end is provided with any suitable form of circuit connecting means such as the integral tab ii. In the form illustrated, the convolutions are enclosed within a terminal portion is of the sheet I! which, as shown, is exterlorly ofrectangular 3 shape. that is, the original shape of the metal sheet it. The other terminal connection to the antenna can be made, for example, by means or the pigtail ll. As clearly illustrated in Figure l, the central portion of the sheet I! is cut out so that the convolutions l3 terminate at their inner end at the tab II. This iorms a true loop antenna in accordance with well known principles in the art of radio communications. In this connection it will be apparent that in providing the unit composed of the insulating panel and the attached metal sheet I! that the metal sheet can originally be in the form of a hollow configuration so that the central area is open eliminating the necessity of removing the central portion or the sheet not cut into convolutions. This modiflcation is a matter of economy in material and labor costs.

This physical structure is capable of manufacture by means oi a simple operation which may be assigned to an automatic machine such as a punch press. The back panel In with the attached metal sheet I! is laid on a platen with the metal sheet lacing upwardly, for example, and positioned with respect to a vertical reciprocable die 20, a sectional view of a portion of which is shown in Figure 3. The die will consist of a block of suitable material such as is commonly used for such dies, such as steel, having formed on the end face thereof a continuous groove 2| forming a continuous helical cutting edge which appears at 22 in this figure. When this die is forced against the metal sheet I! under sufllcient pressure, it will be seen that in one stroke it will cut the thin metal sheet l2 into the structure previously described. The convolutions I! will, in cross-sectional shape, be of arcuate form as is clearly illustrated in Figure 3. The cutting edges 22 will bite into the panel It to form the acutely angled grooves ll and by this same action separate the severed edges of the adjacent convolutions II to provide an air gap between them. An automatically operating punch press when fed with units comprising the panel ill and attached metal sheet l2 can cut the sheet into a loop antenna with one blow. The crimping, bending or deforming oi the convolutions l3 as they are formed by this cutting operation will serve to further clinch them to the panel HI and hold them in place.

It will be seen that by this simple procedure a combined back and antenna tor a radio receivin set can be inexpensively produced on a high production rate basis with a very minimum of hand labor required.

As alternative methods oi proceedingby means or which the resulting article would come within the scope of the claims hereof, it is contemplated that the convolutions comprising the antenna either in the form illustrated herein or equivalent iorms can be applied to the insulating sheet ll by electroplating or by application under prusure by what might be termed branding." It is also within the scope or this invention to form the convolutions from a sheet of metal by cutting methods to form the spaces il by variom well known metal cutting machines.

It will be apparent to those skilled in the art that the details of the subject matter herein disclosed are capable of considerable variation without departure from the novel subject matter thereof and I do not, therefore, desire to be strictly limited to the specific embodiment dlsclosed herein for illustrative purposes but rather to the scope of the claims granted me.

What is claimed is:

1. An air dielectric inductance comprising a panel of insulating material and a continuous metal strip formed from a metal sheet and at tached to one face 0! said panel in the form of a spiral, the planar width of said strip being equal to the pitch of said spiral and said strip being in channel form to provide a free air space between adjacent turns of said spiral.

2. An electrical device comprising a panel of insulating material and an inductance formed from a sheared sheet of metal, attached to one face of the panel, consisting of a plurality of spaced convolutions in spiral arrangement. the convolutions forming a single continuous cmductor defined by a single shear line and the planar width of the conductor being equal to the pitch of said convolutions.

3. An inductance for electrical circuits comprising a panel of insulating material and a continuous ribbon conductor of non-planar crosssection secured to one race thereof in spiral convolutions, said conductor being formed from a sheared sheet of metal and the planar width of said conductor being equal to the pitch oi said spiral.

ALBERT W. FRANKLIN. 

